JP2001056463A - Liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device capable of light display of white and display of a color image having excellent color quality. SOLUTION: This liquid crystal display device has a pair of front and rear substrates 1 and 2 opposed to each other interposing a liquid crystal layer 10. And a polarizing plate 11 is disposed in front of the front substrate 1 and a reflection plate 14 is disposed in the rear of the rear substrate 2. And color filters 7R, 7G and 7B of three color of red, green and blue corresponding to plural picture elements are provided between the liquid crystal layer 10 and the reflection plate 14 and a polarized light reflecting layer 8 which reflects incident light of a component of polarized light along a reflection axis and transmits incident light of a component of polarized light along a transmission axis is provided between the color filter 7R, 7G and 7B and the liquid crystal 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display for displaying a color image.

[0002]

2. Description of the Related Art A liquid crystal display device includes a TN (twisted nematic) type liquid crystal display device and an STN (Super.
There are a (twisted nematic) type liquid crystal display device and a ferroelectric liquid crystal display device using a ferroelectric liquid crystal or an antiferroelectric liquid crystal.

In these liquid crystal display devices, electrodes forming a plurality of pixel regions by regions facing each other are provided on the inner surfaces of a pair of front and rear substrates that face each other with a liquid crystal layer interposed therebetween. Polarizing plates are arranged on the front surface of the front substrate and behind the rear substrate, respectively.

There are two types of liquid crystal display devices, one displaying a black-and-white image and the other displaying a multi-color image such as a full-color image. A plurality of colored layers corresponding to the plurality of pixel regions, for example, three color filters of red, green, blue or yellow, magenta, and cyan are provided on an inner surface of a substrate (generally, a front substrate). ing.

Further, the liquid crystal display device has a backlight, and a transmissive type that displays by using illumination light from the backlight and a display that uses external light such as natural light or indoor light. There is a reflection type liquid crystal display device, and a reflection type liquid crystal display device is conventionally configured by disposing a reflection plate behind the liquid crystal display device (the back surface of the rear polarizing plate).

[0006]

However, in a conventional reflection type liquid crystal display device for displaying a color image, colored light (red, red,
Green, blue or yellow, magenta, and cyan colored light), and various colors including white are displayed by mixing these colored lights.
There is also a problem that the color quality of the displayed image is poor.

That is, the conventional reflection type liquid crystal display device is
A reflection plate is disposed behind the reflection plate, and external light incident from the front is transmitted through the front polarizing plate and the coloring layer and the liquid crystal layer and the rear polarizing plate in order, and is reflected by the reflection plate. Are sequentially transmitted through the rear polarizing plate, the liquid crystal layer, the colored layer, and the front polarizing plate, and are emitted forward.

Therefore, the conventional reflection type liquid crystal display device is
The light emitted from each pixel region is always colored light, and the colored light absorbs the light of the wavelength component in the absorption wavelength band by the colored layer and is colored in the color of the colored layer. Light.

[0009] For example, red, green,
In the case of a liquid crystal display device provided with three color filters of blue, conventionally, white is displayed by an additive color mixture of three colors of red, green, and blue emitted from three adjacent pixel regions. Since the red, green, and blue outgoing light are all light whose intensity has been greatly reduced by absorption in the color filter, the displayed white is a dark display.

In addition, since the conventional liquid crystal display device displays white by mixing color light of a plurality of colors, the emission intensity of the color light of the plurality of colors is adjusted to a good white color without banding. Must be adjusted so that the absorption characteristics and layer thicknesses of the colored layers of the plurality of colors must be set with priority given to white display.

Therefore, in the conventional liquid crystal display device, it is difficult to increase the color purity of the colored light of each color emitted from each pixel region, and therefore, a color image with good color quality cannot be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reflective liquid crystal display device capable of displaying a bright white color image and a good color image.

[0013]

According to the liquid crystal display device of the present invention, electrodes are formed on each inner surface of a pair of front and rear substrates facing each other with a liquid crystal layer interposed therebetween to form a plurality of pixel regions by regions facing each other. A polarizing plate is disposed on a front surface of a front substrate of the pair of substrates, a reflection unit is disposed behind a rear substrate, and the plurality of pixel regions are disposed between the liquid crystal layer and the reflection unit. Are provided with a plurality of colored layers respectively corresponding to the liquid crystal layer, between these colored layers and the liquid crystal layer, having a reflection axis and a transmission axis in directions substantially orthogonal to each other, and a polarization component along the reflection axis. Reflects the incident light of
A polarized light reflecting layer for transmitting incident light of a polarized component along the transmission axis is provided.

Since the liquid crystal display device of the present invention has the above-described configuration, light incident from the front and transmitted through the polarizing plate and the liquid crystal layer is incident on the polarizing reflection layer, and of the light, The light of the polarization component along the reflection axis of the polarization reflection layer is reflected by the polarization reflection layer, passes through the liquid crystal layer and the polarizing plate, and is emitted forward.

The light reflected by the polarized light reflecting layer and emitted forward is not absorbed by the colored layer because the polarized light reflecting layer is provided between the liquid crystal layer and the colored layer. Intense white light.

Further, of the light incident from the front, transmitted through the polarizing plate and the liquid crystal layer, and incident on the polarization reflection layer, the light of the polarization component along the transmission axis of the polarization reflection layer is the polarized light. The light passes through the reflective layer and is incident on the colored layer, and the colored layer absorbs the light of the wavelength component in the absorption wavelength band to become colored light, and the colored light is reflected by the reflection means,
The light passes through the coloring layer, the polarizing reflection layer, the liquid crystal layer, and the polarizing plate in order, and is emitted forward.

That is, the liquid crystal display device reflects the light incident from the front by the polarization reflection layer to display white, and transmits the colored light transmitted through the polarization reflection layer and transmitted through the colored layer to the reflection. Means for displaying the color of the colored layer by reflection by means, and the ratio of white light to colored light emitted from each pixel region is transmitted through the polarizing plate and the liquid crystal layer and is incident on the polarized light reflecting layer. It changes according to the polarization state of the emitted light.

That is, the light incident from the front is converted into linearly polarized light by absorbing the light of the vibration component along the absorption axis by the polarizing plate, and the alignment state of the liquid crystal molecules in the process of transmitting the light through the liquid crystal layer. To receive the birefringence action according to
The polarization state of the light incident on the polarization reflection layer changes according to the alignment state of the liquid crystal molecules, thereby changing the ratio of white light and colored light emitted from each pixel region.

Therefore, by controlling the voltage applied between the electrodes in each pixel region and changing the alignment state of the liquid crystal molecules to control the ratio of white light to colored light emitted from each pixel region, While changing the display of the area to white display and colored display, the color density and brightness of the colored display determined by the ratio of the white light and the colored light are controlled, and the color mixture of the light emitted from each pixel area is performed. A color image can be displayed.

As described above, the liquid crystal display device of the present invention
Light incident from the front is reflected by the polarization reflection layer to display white, and light reflected by the polarization reflection layer and emitted forward is high-intensity white light that is not absorbed by the coloring layer at all. Since the light is light, bright white can be displayed.

In addition, since this liquid crystal display device displays white by reflecting light incident from the front by the polarizing reflection layer, a conventional liquid crystal device that displays white by mixing a plurality of colors of colored light. As in the case of a display device, it is not necessary to adjust the emission intensities of the colored lights of the plurality of colors so as to obtain a good white color with no banding. Therefore, the absorption characteristics and the layer thickness of the colored layers of the plurality of colors are not required. Are set so that colored light with high color purity can be obtained, and a color image with good color quality can be displayed.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, a liquid crystal display device of the present invention has a polarizing plate disposed on the front surface of a front substrate of a pair of front and rear substrates sandwiching a liquid crystal layer, and is provided behind a rear substrate. In addition to disposing a reflection means, between the liquid crystal layer and the reflection means, provided a plurality of colored layers corresponding to a plurality of pixel regions, respectively, between these colored layers and the liquid crystal layer, By providing a polarization reflection layer that reflects the incident light of the polarization component along the reflection axis and transmits the incident light of the polarization component along the transmission axis, even if it is a reflection type, the white display is bright, Further, a color image with good color quality can be displayed.

In the liquid crystal display device according to the present invention, the plurality of colored layers may be provided on either the inner surface side or the rear surface side of the rear substrate as long as the colored layer is between the liquid crystal layer and the reflection means. Further, the polarization reflection layer may be provided on either the inner surface side or the back surface side of the rear substrate as long as it is between the coloring layer and the liquid crystal layer.

That is, for example, when both the polarizing reflection layer and the coloring layer are provided on the inner surface side of the rear substrate, the coloring layer is provided on the inner surface of the rear substrate, and the polarizing reflection layer is formed on the coloring layer. It may be provided. When both the polarization reflection layer and the coloring layer are provided on the back side of the rear substrate, the polarization reflection layer is provided on the rear surface of the rear substrate, and the coloring layer may be provided on the rear surface of the polarization reflection layer. In any configuration, a white display is bright and a color image with good color quality can be displayed.

Further, the colored layers of the plurality of colors are red,
Three color filters of green, blue or yellow, magenta, and cyan are preferable, and by providing these three color filters, a multicolor image such as a full-color image can be displayed.

[0026]

1 to 3 show a first embodiment of the present invention. FIG. 1 is a cross-sectional view of a liquid crystal display device without hatching.

In this liquid crystal display device, transparent electrodes 4 and 6 forming a plurality of pixel regions by regions facing each other are formed on inner surfaces of a pair of front and rear transparent substrates 1 and 2 facing each other with a liquid crystal layer 10 interposed therebetween. Is provided, and the pair of substrates 1 and 2 are provided.
A polarizing plate 11 is arranged on the front surface of the front substrate 1, a reflecting plate 14 is arranged behind the rear substrate 2 as a reflecting means, and the plurality of liquid crystal layers are arranged between the liquid crystal layer 10 and the reflecting plate 14. , A plurality of colored layers respectively corresponding to the pixel regions, for example, red, green and blue color filters 7R, 7G, 7
B, and these color filters 7R, 7G, 7
The configuration is such that a polarization reflection layer 8 is provided between B and the liquid crystal layer 10.

The polarizing plate 11 is an uncolored polarizing plate generally called a neutral polarizing plate, and the reflecting plate 14 is made of a metal film such as aluminum or silver or a white film such as barium titanate. It is an uncolored reflection plate.

The liquid crystal display of this embodiment is of a simple matrix type, and the electrodes 4 provided on one substrate, for example, the inner surface of the front substrate 1, are arranged along the row direction (the horizontal direction of the screen). The plurality of scanning electrodes formed in parallel with each other, and the plurality of electrodes 6 provided on the inner surface of the rear substrate 2, which is the other substrate, are formed in parallel with each other along the column direction (vertical direction of the screen). Signal electrodes.

In this embodiment, the color filter 7
R, 7G, and 7B are provided on the inner surface of the rear substrate 2, the polarization reflection layer 8 is provided on the color filters 7R, 7G, and 7B, and the signal electrode 6 is provided on the polarization reflection layer 8.
Is provided.

FIG. 3 is a perspective view of the polarization reflection layer 8.
The polarization reflection layer 8 has a reflection axis 8s and a transmission axis 8p in directions substantially orthogonal to each other, reflects incident light of a polarization component along the reflection axis 8s, and reflects a polarization component of the polarization component along the transmission axis 8p. It has the property of transmitting incident light.

That is, as shown in FIG. 3, a polarization component (hereinafter, referred to as a polarization component) along the reflection axis 8s is provided on the polarization reflection layer 8.
When light including both the light s of the S-polarized light component and the light p of the polarized light component (hereinafter referred to as the P-polarized light component) along the transmission axis 8p is incident, the reflection axis of the incident light is reflected. The light s of the S-polarized component along 8s is reflected by the polarization reflection layer 8, and the light p of the P-polarization component along the transmission axis 8p passes through the polarization reflection layer 8. Although FIG. 3 shows an example in which light is incident on the polarization reflection layer 8 from the front side, the polarization reflection layer 8 has the same characteristics with respect to the incident light from the rear side.

The polarization reflection layer 8 has the same structure as an optical film generally called a polarization reflection plate. For example, the color filter 7 provided on the inner surface of the rear substrate 2 is used.
The optical film is formed by attaching the optical film on R, 7G, and 7B. The polarization reflection layer 8 has reflection characteristics and transmission characteristics that do not have wavelength dependence, and the reflected light is specular reflection light.

Further, alignment films 5 and 9 are formed on the inner surfaces of the pair of substrates 1 and 2 to cover the electrodes 4 and 6, respectively. The alignment treatment is performed by rubbing in a predetermined direction.

The pair of substrates 1 and 2 are joined via a frame-shaped sealing material 3.
Liquid crystal is filled in a region surrounded by the sealing material 3 between the two to form a liquid crystal layer 10.

The liquid crystal display of this embodiment has
The liquid crystal molecules of the liquid crystal layer 10 are N-type, and the alignment direction in the vicinity of each of the substrates 1 and 2 is regulated by the alignment films 5 and 9 provided on the inner surfaces of the pair of substrates 1 and 2, 180 ° to 270 ° between the pair of substrates 1 and 2
, For example, at a twist angle of 220 ° to 240 °.

In this STN type liquid crystal display device, since the twist angle of the liquid crystal molecules is large, the change in the light transmittance with respect to the change in the alignment state of the liquid crystal molecules due to the application of a voltage between the electrodes 4 and 6 is sharp. Therefore, time-division driving at a higher duty is possible as compared with the TN type in which the twist angle of the liquid crystal molecules is approximately 90 °, however, on the other hand, since the display is colored, In this example, a phase difference plate 12 for color compensation is provided between a polarizing plate 11 disposed on the front surface of the front substrate 1 and the front substrate 1.

The phase difference plate 12 has a Δ
nd (the product of the birefringence Δn of the liquid crystal and the thickness d of the liquid crystal layer), and has an optical axis of each of the polarizing plate 11, the retardation plate 12, and the polarizing reflection layer 8. Is set according to the alignment state of the liquid crystal molecules of the liquid crystal layer 10, the Δnd of the liquid crystal layer 10 and the retardation value of the retardation plate 12, so as to eliminate the banding of the display.

FIG. 2 shows that the alignment state of the liquid crystal molecules in the liquid crystal layer 10 is a twist alignment with a twist angle of 220 ° to 240 °, and the Δnd of the liquid crystal layer 10 is 300 to 700 n.
m, the retardation of the retardation plate 12 is 300 to 70
When set to 0 nm, the alignment state of the liquid crystal molecules,
The directions of the absorption axis 11a of the polarizing plate 11, the slow axis 12a of the phase difference plate 12, the reflection axis 8s and the transmission axis 8p of the polarization reflection layer 8 are shown.

As shown in FIG. 2, in this embodiment, the front substrate 1
Of the liquid crystal molecule alignment direction 1a in the vicinity of
And the liquid crystal molecule orientation direction 2a in the vicinity of the rear substrate 2 from the front side (the front side of the liquid crystal display device) when viewed from the front side (the front side of the liquid crystal display device). The liquid crystal molecules of the liquid crystal layer 10 are set in a direction deviated counterclockwise by 20 ° to 30 °, so that the twist direction of the liquid crystal layer 10 is shifted from the rear substrate 2 to the front substrate 1 as shown by a broken arrow in the drawing. To the right, 220 ° to 2 clockwise as viewed from the front
It is twist-oriented at a twist angle of 40 °.

The polarizing plate 11 has its absorption axis 1
1a is disposed in a direction deviated counterclockwise by approximately 5 ° to 15 ° with respect to the horizontal axis x from the front side, and the retardation plate 12 has its slow axis 12a It is arranged in a direction deviated counterclockwise by 40 ° to 50 ° with respect to x. That is, the absorption axis 11a of the polarizing plate 11 is rotated counterclockwise by 25 ° to 4 ° with respect to the liquid crystal molecule alignment direction 1a near the front substrate 1.
5 °, the slow axis 12a of the phase difference plate 12 is
It is shifted counterclockwise by 35 ° to 45 ° from the absorption axis 11a of the polarizing plate 11 when viewed from the front side.

The polarized light reflecting layer 8 has a reflection axis 8
s is 70 ° counterclockwise with respect to the horizontal axis x when viewed from the front side.
It is provided in a direction shifted by about 80 °. That is, the reflection axis 8s of the polarized light reflection layer 8 is substantially 50 ° counterclockwise as viewed from the front side with respect to the liquid crystal molecule alignment direction 2a near the rear substrate 2, and is substantially orthogonal to the reflection axis 8s. The transmission axis 8p is shifted approximately 20 ° clockwise from the front side with respect to the liquid crystal molecule alignment direction 2a near the rear substrate 2.

Further, in this embodiment, since the light reflected by the polarization reflection layer 8 (specular reflection light) is diffused and emitted in a wide range, the light is reflected between the polarizing plate 11 and the front substrate 1.
The light diffusion layer 13 is provided.

In FIG. 1, the light diffusion layer 13 is provided on the back side of the phase difference plate 12 (between the phase difference plate 12 and the front substrate 1). It may be provided on the front side of the retardation plate 12 (between the retardation plate 12 and the polarizing plate 11).

Since this liquid crystal display device has the above-described structure, light incident from the front and transmitted through the polarizing plate 11, the phase difference plate 12, and the liquid crystal layer 10 is reflected by the polarizing reflection layer 8
And the reflection axis 8 of the polarization reflection layer 8 of the light
Light having a polarization component along s (light s having an S-polarization component in FIG. 3) is reflected by the polarization reflection layer 8 and passes through the liquid crystal layer 10, the phase difference plate 12, and the polarization plate 11, and is emitted forward. I do.

The light reflected by the polarization reflection layer 8 and emitted forward is reflected by the color filter because the polarization reflection layer 8 is provided between the liquid crystal layer 10 and the color filters 7R, 7G, and 7B. Non-colored light that does not receive any absorption by 7R, 7G, and 7B, that is, high-intensity white light.

The light incident from the front is converted into linearly polarized light by absorbing the light of the vibration component along the absorption axis 11 a by the polarizing plate 11, and the light is polarized by the birefringence of the phase difference plate 12. While changing the state, it undergoes a birefringence action according to the alignment state of the liquid crystal molecules in the process of transmitting through the liquid crystal layer 10, and the light enters the polarization reflection layer 8, and of the light, the polarization reflection layer The light of the polarization component along the reflection axis 8s of 8 is reflected by the polarization reflection layer 8.

Then, the light reflected by the polarization reflection layer 8 passes through the liquid crystal layer 10 and the retardation plate 12 again, enters the polarization plate 11, and is absorbed by the polarization plate 11 out of the light. Light having a polarization component along the axis 11a is absorbed by the polarizing plate 11, and light transmitted by the polarizing plate 11 is emitted forward.

Therefore, the intensity of the white light reflected by the polarizing reflection layer 8 and emitted forward is equal to the intensity of the polarizing plate 11.
And the phase difference plate 12 changes according to the polarization state of the light that passes through the liquid crystal layer 10 and enters the polarization reflection layer 8.

Also, of the light incident from the front, transmitted through the polarizing plate 11, the retardation plate 12, and the liquid crystal layer 10, and incident on the polarizing reflection layer 8, the transmission axis 8p of the polarizing reflection layer 8 is used.
The light of the polarization component along the line (the light p of the P polarization component in FIG. 3) passes through the polarization reflection layer 8 and is incident on the color filters 7R, 7G, and 7B.
R, 7G, and 7B absorb the light of the wavelength component in the absorption wavelength band to become colored light, and the colored light is reflected by the reflection plate 1.
4 and reflected by the color filters 7R, 7G, 7
B, the polarization reflection layer 8, the liquid crystal layer 10, and the retardation plate 12
And the polarizing plate 11 are sequentially transmitted and emitted forward.

The colored light passes through the polarizing reflection layer 8 among the light incident from the front, and
R, 7G, and 7B are light that has been absorbed and colored by the light of the wavelength component in the absorption wavelength band. Therefore, the intensity of the colored light that is emitted forward also depends on the polarization plate 11 and the phase difference plate 12.
It changes according to the polarization state of the light that passes through the liquid crystal layer 10 and enters the polarization reflection layer 8.

That is, in this liquid crystal display device, light incident from the front is reflected by the polarization reflection layer 8 to display white, and the color filter 7 transmits through the polarization reflection layer 8 to display white.
The light transmitted through R, 7G, and 7B is colored by the reflection plate 14.
To reflect the color of the color filters 7R, 7G, 7B, and the ratio between the white light and the colored light emitted from each pixel area is determined by the polarization plate 11 and the retardation plate 12
It changes according to the polarization state of the light that passes through the liquid crystal layer 10 and enters the polarization reflection layer 8.

That is, as described above, the light incident from the front is absorbed by the polarizing plate 11 into the light of the vibration component along the absorption axis 11a and becomes linearly polarized light. The polarization state is changed by the birefringence effect, and the birefringence is applied to the polarization reflection layer 8 according to the alignment state of the liquid crystal molecules because it undergoes the birefringence action according to the alignment state of the liquid crystal molecules in the process of transmitting through the liquid crystal layer 10. The polarization state of the emitted light changes, thereby changing the ratio between the white light and the colored light emitted from each pixel region.

Accordingly, by controlling the voltage applied between the electrodes 4 and 6 in each pixel region to change the alignment state of the liquid crystal molecules and to control the ratio of white light to colored light emitted from each pixel region. The display of each pixel area is changed between white display and colored display, and the color intensity and brightness of the colored display determined by the ratio of the white light to the colored light are controlled, and the light emitted from each pixel area is controlled. A color image can be displayed by mixing the colors.

In this embodiment, the alignment state of the liquid crystal molecules in the liquid crystal layer 10 and the absorption axis 11a of the polarizing plate 11
Since the direction of the slow axis 12a of the phase difference plate 12 and the directions of the reflection axis 8s and the transmission axis 8p of the polarization reflection layer 8 are set as shown in FIG. When an off voltage is applied so that the liquid crystal molecules are oriented in the initial twist alignment state in which the liquid crystal molecules are most inclined with respect to the surfaces of the substrates 1 and 2, the display in the pixel region becomes white and the liquid crystal molecules are When an on-voltage that rises and orients substantially perpendicular to the surfaces of the substrates 1 and 2 is applied, the display of the pixel region becomes the color of the color filters 7R, 7G, and 7B.

Further, the liquid crystal display device of this embodiment includes three color filters 7R, 7G, 7B of red, green, and blue as colored layers of a plurality of colors. By controlling the density and brightness of red, green, and blue light, a multicolor image such as a full-color image can be displayed.

As described above, the liquid crystal display device reflects the light incident from the front by the polarization reflection layer 8 to display white, and the light reflected by the polarization reflection layer 8 and emitted forward. Are the color filters 7R, 7G,
Since this is high-intensity white light that is not absorbed by 7B at all, bright white can be displayed.

Further, since this liquid crystal display device displays white by reflecting light incident from the front by the polarization reflection layer 8, a conventional white display by mixing a plurality of colors of colored light. As in a liquid crystal display device, it is not necessary to adjust the emission intensities of the colored lights of the plurality of colors so that good white without banding can be obtained.
By setting the absorption characteristics and the layer thicknesses of the green and blue color filters 7R, 7G, and 7B so as to obtain colored light with high color purity, a color image with good color quality can be displayed.

The liquid crystal display device of this embodiment is of the STN type capable of high-duty time-divisional driving. The polarizing plate 11 disposed on the front surface of the front substrate 1 and the front substrate 1 Since the retardation plate 12 is provided between the two, it is possible to almost eliminate display banding which is a problem in the STN type liquid crystal display device.

That is, considering the case where the retardation plate 12 is not provided, the liquid crystal display device of this embodiment has the polarizing plate 1
1 is obliquely shifted with respect to the liquid crystal molecule alignment direction 1a in the vicinity of the front substrate 11, the linearly polarized light transmitted through the polarizing plate 11 and incident on the liquid crystal layer 10 is Each wavelength light becomes elliptically polarized light having a different polarization state due to refraction, and the light enters the polarization reflection layer 8.

The polarization reflection layer 8 reflects the incident light of the polarization component along the reflection axis 8s and transmits the incident light of the polarization component along the transmission axis 8p. When the incident light is the above-mentioned light in which each wavelength light is elliptically polarized light having a different polarization state, the reflected light and the transmitted light respectively have different light intensities for each wavelength light in the visible light band. The light becomes a light having a spectral intensity distribution and is colored in a color corresponding to the spectral intensity distribution.

Therefore, when the retardation plate 12 is not provided, white displayed by the light reflected by the polarization reflection layer 8 takes on a certain color, and passes through the polarization reflection layer 8 and passes through the color filters 7R and 7R. A color shift occurs in the color displayed by the light colored and emitted in the colors 7G and 7B.

However, in this embodiment, the polarizing plate 11
Since the retardation plate 12 having a retardation set according to Δnd of the liquid crystal layer 10 is provided between the liquid crystal layer 10 and the front substrate 1, each wavelength light is polarized by the birefringence of the liquid crystal layer 18. The elliptically polarized light in different states is compensated for by the birefringence of the retardation plate 12 so as to eliminate the banding of the display. By compensating by the action, the above-mentioned banding of light is eliminated, and a color image of good color quality is displayed without a banding of white display and a color shift of a display color by the color filters 7R, 7G, 7B. it can.

In this embodiment, the polarizing plate 11
Since the light diffusion layer 13 is provided between the substrate and the front substrate 1, even if the white light reflected by the polarization reflection layer 8 is specular reflection light, the white light is diffused over a wide range and While being emitted, the colored light transmitted through the polarization reflection layer 8 and colored by the color filters 7R, 7G, and 7B and reflected by the reflection plate 14 can be diffused over a wide range and emitted forward. Therefore, a wide viewing angle can be obtained.

In the first embodiment, the color filters 7R, 7G, 7B are provided on the inner surface of the rear substrate 2, and the polarization reflection layer 8 is provided on the color filters 7R, 7G, 7B. The color filters 7R, 7G, 7B are:
Between the liquid crystal layer 10 and the reflection plate 14, the rear substrate 2
May be provided on either the inner surface side or the rear surface side of the color filter. The polarizing reflection layer 8 may be provided on the color filters 7R, 7G, 7B.
May be provided on either the inner surface side or the rear surface side of the rear substrate as long as it is between the liquid crystal layer 10.

FIG. 4 is a sectional view of a liquid crystal display device according to a second embodiment of the present invention, in which hatching is omitted. In the liquid crystal display device of this embodiment, the polarization reflection layer 8 is provided on the back surface of the rear substrate 2. And a red, green, and blue 3
The color filters 7R, 7G, and 7B are provided.

In the liquid crystal display device of this embodiment, both the polarization reflection layer 8 and the color filters 7R, 7G, 7B are provided on the back surface of the rear substrate 2. Since the configuration is the same as that of the liquid crystal display device of the embodiment of FIG.

Also in this embodiment, a red color is applied between the liquid crystal layer 10 and the reflection plate 14 provided behind the rear substrate 2.
Three color filters 7R, 7G, 7B of green and blue are provided, and a reflection axis 8 is provided between the color filters 7R, 7G, 7B and the liquid crystal layer 10 in a direction substantially orthogonal to each other.
s and a transmission axis 8p, the polarization reflection layer 8 that reflects incident light having a polarization component along the reflection axis 8s and transmits incident light having a polarization component along the transmission axis 8p is provided.
As in the first liquid crystal display device described above, a white display is bright and a color image with good color quality can be displayed.

In the first and second embodiments,
Although a light diffusion layer 13 is provided between the polarizing plate 11 disposed on the front surface of the front substrate 1 and the front substrate 1, the light diffusion layer 13 is omitted, and the polarization reflection layer 8 has a reflection axis 8s. A wide viewing angle may be obtained by providing the function of scattering and reflecting the polarized light components along the light, and using the reflection plate 14 provided behind the rear substrate 2 as a scattering reflection plate.

The liquid crystal display device of each of the above embodiments has three color filters 7R, 7G and 7B of red, green and blue as colored layers of a plurality of colors. The coloring layer is not limited to the three color filters of red, green, and blue, and may include, for example, three color filters of yellow, magenta, and cyan to display a multicolor image.

Further, the liquid crystal display device of each of the above embodiments is
Although the present invention is of the STN type, the present invention is directed to a TN in which liquid crystal molecules of a liquid crystal layer are twist-aligned, for example, at a twist angle of about 90.
The present invention can be applied to an N-type liquid crystal display device or a ferroelectric liquid crystal display device using a ferroelectric liquid crystal or an antiferroelectric liquid crystal. May be omitted.

The liquid crystal display device of each of the above embodiments is of a simple matrix type. However, the present invention provides a liquid crystal display device having an inner surface of one of a pair of front and rear substrates which face each other with a liquid crystal layer interposed therebetween. A plurality of pixel electrodes arranged in a matrix, a plurality of active elements (for example, thin film transistors) respectively connected to the pixel electrodes, and a plurality of wirings for supplying signals to the plurality of active elements are provided; The present invention can also be applied to an active matrix type liquid crystal display device in which a counter electrode facing the plurality of pixel electrodes is provided on the inner surface of the other substrate.

Also in the case of this active matrix liquid crystal display device, a polarizing plate is arranged on the front surface of the front substrate, and the reflection means is arranged behind the rear substrate, and a plurality of reflection plates are provided between the liquid crystal layer and the reflection means. A plurality of colored layers corresponding to the pixel regions are provided, respectively, and between these colored layers and the liquid crystal layer, the incident light of the polarization component along the reflection axis is reflected, and the polarization component of the polarization component along the transmission axis is reflected. By providing the polarization reflection layer that transmits incident light, a white image can be displayed brightly and a color image with good color quality can be displayed.

Further, the liquid crystal display device of the above embodiment performs only the reflection type display using external light using the reflection plate 14 as the reflection means disposed behind the rear substrate 2. The present invention can also be applied to a so-called two-way display type liquid crystal display device that performs both a reflection type display using external light and a transmission type display using illumination light from behind.

That is, the two-way display type liquid crystal display device performs reflection type display using external light in an environment of high illuminance where sufficient external light can be obtained, resulting in insufficient external light brightness. Sometimes, the lack of screen luminance due to the reflective display using external light is compensated for by the combined use of the transmissive display using the illumination light, and the two-way liquid crystal display device has sufficient brightness. It can be used even in a low illuminance environment where external light cannot be obtained.

Since the liquid crystal display device of the present invention displays white by reflection of external light by the polarizing reflection layer, the brightness of the white display can be improved even when the transmission type display using the illumination light is used together. The brightness is the brightness corresponding to the intensity of the external light incident from the front, but the light reflected by the polarization reflection layer is light that does not receive any absorption by the coloring layer, and thus the light incident from the front is If the intensity is higher than a certain level, white display with sufficient brightness can be obtained.

When the present invention is applied to the two-way display type liquid crystal display device, the reflecting means disposed behind the rear substrate 2 is a semi-transmissive reflecting plate, and the entire front surface is illuminated behind the semi-transmissive reflecting plate. A backlight that emits light may be provided. As the reflecting means, for example, 100% of light from a light source is theoretically emitted as described in the specification and drawings of 1997 Patent Application No. 353603. However, if a device that reflects 100% of the incident light from the front is used, the illumination light from the light source can be emitted as the illumination light with high efficiency, and the incident light from the front can be reflected with a high reflectance.

[0078]

According to the liquid crystal display device of the present invention, the polarizing plate is arranged on the front surface of the front substrate of the pair of front and rear substrates sandwiching the liquid crystal layer, and the reflecting means is arranged behind the rear substrate. Providing a plurality of colored layers corresponding to a plurality of pixel regions, respectively, between the liquid crystal layer and the reflection unit, and a polarization component along a reflection axis between the colored layers and the liquid crystal layer. Because it is provided with a polarization reflection layer that reflects the incident light of and transmits the incident light of the polarization component along the transmission axis,
Even in the case of the reflection type, a white display is a bright display without absorption by the coloring layer, and a color image with good color quality can be displayed.

In the liquid crystal display device according to the present invention, the plurality of colored layers may be provided on either the inner surface side or the rear surface side of the rear substrate as long as the colored layer is between the liquid crystal layer and the reflection means. Further, the polarization reflection layer may be provided on either the inner surface side or the back surface side of the rear substrate as long as it is between the coloring layer and the liquid crystal layer.

That is, for example, when both the polarizing reflection layer and the coloring layer are provided on the inner surface side of the rear substrate, the coloring layer is provided on the inner surface of the rear substrate, and the polarizing reflection layer is formed on the coloring layer. It may be provided. When both the polarization reflection layer and the coloring layer are provided on the back side of the rear substrate, the polarization reflection layer is provided on the rear surface of the rear substrate, and the coloring layer may be provided on the rear surface of the polarization reflection layer. In any configuration, a white display is bright and a color image with good color quality can be displayed.

Further, the colored layers of the plurality of colors are red,
Three color filters of green, blue or yellow, magenta, and cyan are preferable, and by providing these three color filters, a multicolor image such as a full-color image can be displayed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a liquid crystal display device according to a first embodiment of the present invention, in which hatching is omitted.

FIG. 2 is a diagram illustrating an alignment state of liquid crystal molecules in a liquid crystal layer, an absorption axis of a polarizing plate, and a slow axis of a retardation plate in the liquid crystal display device.
The figure which shows the direction of the reflection axis and transmission axis of a polarization reflection layer.

FIG. 3 is a perspective view of a polarization reflection layer.

FIG. 4 is a sectional view of a liquid crystal display device according to a second embodiment of the present invention, in which hatching is omitted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... front board | substrate 2 ... rear board | substrate 4, 6 ... electrode 5, 9 ... orientation film 7R, 7G, 7B ... color filter (coloring layer) 8 ... polarization reflection layer 8s ... reflection axis 8p ... transmission axis 10 ... liquid crystal layer 11 ... Polarizing plate 12 ... Phase plate 13 ... Diffusion layer 14 ... Reflector (reflection means)

Claims (4)

[Claims] An electrode for forming a plurality of pixel regions by regions facing each other is provided on each inner surface of a pair of front and rear substrates facing each other with a liquid crystal layer interposed therebetween, and an electrode of a front substrate of the pair of substrates is provided. A polarizing plate is arranged on the front surface, a reflecting means is arranged behind the rear substrate, and a plurality of colored layers respectively corresponding to the plurality of pixel regions are provided between the liquid crystal layer and the reflecting means. Between the colored layer and the liquid crystal layer, has a reflection axis and a transmission axis in directions substantially orthogonal to each other, reflects incident light of a polarization component along the reflection axis, and extends along the transmission axis. A liquid crystal display device comprising a polarization reflection layer for transmitting incident light having a polarized component. 2. The liquid crystal display device according to claim 1, wherein a coloring layer is provided on the inner surface of the rear substrate, and a polarization reflection layer is provided on the coloring layer. 3. The liquid crystal display device according to claim 1, wherein a polarizing reflection layer is provided on the back surface of the rear substrate, and a coloring layer is provided on the back surface of the polarizing reflection layer. 4. A color filter according to claim 1, wherein the color layers of a plurality of colors are three color filters of red, green, blue or yellow, magenta and cyan. Liquid crystal display.